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Griso 8V Dyno chart - 112,1 bhp / 115,8 Nm

Discussion in 'Griso-Bella Chat & Tech' started by klaas123, Dec 6, 2010.

  1. klaas123

    klaas123 Cruisin' Guzzisti

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    No problem Mi_ka, here we go:

    Power was delivered in 4th gear and it took approx. 8 seconds.
    The Tovami bench measures slippage of the rear wheel and corrects for it in the graph.

    HdeB is a small but highly respected motorcycle tuning company (does not sell bikes) with mostly Dutch and German customers (racing and road use). He is very serious about his work and won't give you incorrect readings from the dyno.
    He mostly works on Ducati (race) bikes but also on "rice cookers".
     
  2. Mi_ka

    Mi_ka High Miler

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    I suppose it was a sweep test (full inertial mode - no dyno braking involved) hence the 8 seconds duration in 4th gear for the 20kgm² roller drum.
    Our company also recommends a duration of 8-10 seconds for sweep inertia tests.
    In inertial mode each dyno manufacturer uses pretty different calculations to assess the inertia of transmission and engine components so inertial mode dyno runs produce different numbers on different dynamometer models.
    These numbers are not directly comparable. You can only compare to numbers produced by same type bikes on the same model benches (provided that the climatic conditions are not too much off despite the correction formulas and of course that the mechanic has not messed things up during the run).

    The only way to know if your 8V has indeed 112 real hps is to do a braked test.
    I am not saying that there are not 112 hp at your rear wheel. I am just saying that in inertial mode we cannot be sure that this number is exact.
    Brake tests produce the same results between different dynos with the only variable being tyre slip depending on tyre/temperature and roller drum surface traction so the error margin is much narrower and power lost due to tyre slip can be evaluated more or less.

    A problem with small duration sweep tests is that conditions inside the combustion chamber differ greatly than steady braked tests so the tuning process is not optimum for best performance under load (e.g chasing maximum speed on open roads) - maybe the engine would deliver different numbers under steady loading.
    Also, if the test is of too short duration/too much acceleration then the ECU might operate under acceleration maps instead of steady load maps so the AFR ratio measured by the dyno would not be the same as the AFR under steady load.

    Anybody knows if the Guzzi ECUs have different acceleration maps?

    On the other hand, most dyno setups have inadequate cooling for extended steady load tests - too expensive to have the full monty of cooling equipment, not feasible for small-medium shops.
    To keep your 8V properly cooled under full load like going full speed on an autobahn it would take more than a 200 000 BTU air conditioner plus a wind tunnel size fan.
    So the tyre suffers overheating, the gas tank gets too warm and the engine is stressed too much to worth doing fully braked tests for all conditions for a street bike.
    Also, in real life most riding conditions are accelerating through city traffic, a twisty road or casually cruising and overtaking on the highway so inertial tests are closer to real life situations.

    So on the dyno there is a give-and-take "cooking" situation and all depends on how good cook the mechanic is to properly prepare the dish.
    And if the cook is good it does not matter so much what kind of oven he uses as long it is adequate for the job.
    If it goes like a blast and you are happy all is good and f@&^ the numbers.
     
  3. jlburgess

    jlburgess Tuned and Synch'ed

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    I have almost identical mods and I was around 97 or 98 on two different Dynojet dynos. Could my map be improved? Sure! Will it ever improve by 14 horsepower - pretty doubtful. That is why I think the dynos are different. Not meaning to insult your tuner or your results. Although it looks to have improved your bike by 10 hp so maybe it is possible?
    Have you noticed any change in your fuel mileage? Seems like carbuerated bikes get about 10 mpg better than most FI bikes I've owned. Still haven't figured out why that is?
     
  4. klaas123

    klaas123 Cruisin' Guzzisti

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    Thanks for all that info Michail, very instructive!

    @ John: What is the exact setup of your 8V? My result may differ a few horsies with another altitude/temp/bench but certainly not in the order of 10hp or more I think.
    Maybe you should not go for "free" dyno runs but go to a reputable tuner and let him build a map for your bike?
     
  5. jlburgess

    jlburgess Tuned and Synch'ed

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    I have Todd's open airbox, PC V, and the map he supplied from another 8V with an autotune. I don't have the AT, I just zeroed out the closed loop area of the map. I have a Zard exhaust. The last time it was dyno'd in that configuration with db killer out it was 98 hp. Since then, Pete loaded an 068 map and I put the db killer in, which greatly improved midrange power. I also went -10% at full throttle 7-8k rpm, but didn't notice a huge power increase.
    I would like to do the dyno runs like you have done, but don't have the funds at this time. It runs great the way it is, so I haven't made it a priority.
     
  6. klaas123

    klaas123 Cruisin' Guzzisti

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    So with a different exhaust and probably air filter (BMC here, not paper but cotton based like K&N) we have a difference of 4hp on Todd's base map. Doesn't sound much to me John..
    And then there are other variables like hight above sea level, temperature etc.
     
  7. jlburgess

    jlburgess Tuned and Synch'ed

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    I have a BMC also. I live in Portland Oregon, so pretty much at sea level.
     
  8. klaas123

    klaas123 Cruisin' Guzzisti

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    Portland Oregon is 52.5 meters above sea level, my run was done at 16 meters a.s.l., not a big difference indeed but then there are so many variables involved.
    Maybe Michail can chime in and tell us some more about the subject?
     
  9. jlburgess

    jlburgess Tuned and Synch'ed

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    So what would it take for you to post that map so we can all see what kind of magic has been performed? Please! :)
     
  10. Mi_ka

    Mi_ka High Miler

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    I suppose on an inertial Dynojet?

    Let me repeat: You cannot directly compare the numbers between different model bench tests done in inertial mode.

    To compensate for test results with differences in air density, temperature, humidity due to altitude and climatic differences there have been various corrective standards developed over the decades.
    These standards by DIN, ISO, SAE or EC have some reference points and increase or decrease the horsepower measured during the test according to the observed climatological data when the test is performed.
    Most of these standards are approximation formulas developed on theoretical approaches and observed carburation behavior of fueling systems under different climatological conditions.

    When comparing numbers you must see that the correction standard used is the same for both tests in order not to compare oranges to apples.

    On your test I see no reference to what correction standard was used - only a CF (correction factor) with no other reference except if the cut SA is SAE correction (and then which SAE?).
    It is not unusual for a shop to display results in the correction standard that gives the bigger numbers because of various reasons:
    The DIN standard was developed in the '50s I think for carburated engines and does not take account of humidity like the more accurate and modern EC95.1 standard that unfortunately gives not so nice but much more accurate numbers.
    Most SAE standards were developed for big V8s and are supposing there are big friction loses that are added to the result as a multiplier percentage.

    However good a correction standard may be, this does not mean that the fueling system behaves linearly over the temperature and barometric range. So when comparing tests done on too different climatological conditions there should be some deviation expected even for the same bike with the same tyre and the same fuel. Our company suggests no bigger difference than 10 degrees Celsius. Unfortunately no word on mBar and condensation differences...
    It is like cooking. Never exact. The ",1" figure is a joke, sorry...
     
  11. jlburgess

    jlburgess Tuned and Synch'ed

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    So Klass, how about posting that map? I'll make a $20 contribution to the website if I can download it....
     

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